Many of our water sources have become contaminated with various types of chemicals which are hazardous to human health. Removal of the contaminants is often difficult and costly, both for large consumers, for example, industrial concerns, and for small consumers, for example, domestic ground water well owners. One type of contaminant which is particularly difficult and costly to remove comprises volatile substances and, more specifically, volatile organic chemicals such as halogenated hydrocarbons. In the context of this invention, volatile substances are generally defined as materials having higher pure component vapor pressures and lower boiling points then water.
Various methods are known for removing halogenated hydrocarbons and other contaminants from water. For example, the Bright U.S. Pat. No. 4,470,909 discloses a method for extracting halogenated hydrocarbons from water by contacting an aqueous solution containing halogenated hydrocarbons with a phosphine oxide. The Rajakovics U.S. Pat. No. 3,990,951 discloses a method for purifying water, particularly radioactive waste water, employing evaporation and degassing steps. The Hartig U.S. Pat. No. 4,341,601 discloses a water evaporation process useful in water desalination and purification wherein water is converted to steam in a falling film evaporator apparatus and the resultant steam is condensed to provide fresh water. The Starmer U.S. Pat. No. 3,501,384 similarly discloses a method for the production of distilled or potable water from sea water or brackish water using a multi-stage flash evaporator in which the water is purified by evaporation. The Pottharst, Jr. U.S. Pat. No. 3,884,767 discloses a similar multi-effect flash evaporator method and apparatus for purifying water, for example, sea water.
With an increasing number of our water sources being contaminated, a need exists for additional methods which are simple and energy efficient for removing the contaminants to provide potable water supplies.